Click here to Skip to main content
15,867,308 members
Articles / Desktop Programming / MFC

Barry's Screen Capture

Rate me:
Please Sign up or sign in to vote.
3.74/5 (26 votes)
11 Jan 20034 min read 270.7K   14.5K   96   38
An article showing methods of screen capture

Sample Image - CapIT.jpg

Introduction

This article demonstrates the methods of capturing different portions of the screen. You have the facility to then save the captured image to a file.

Background

The idea for developing the article came to me when I had downloaded such a utility for capturing screen-shots for use in my articles like this one, on the Internet, but unfortunately the downloaded utility had too many nagging screens and obviously for a no-nags version, I had to pay which I cannot afford. So the only way out was to develop one on my own, the MSDN sample WinCap could have served the purpose but the source was not available on the CD. So I started developing the article in MFC using the Win32 sample provided on the MSDN CD (WinCap). And also so as to be able to capture portions of the screen which I had done sometime ago in Visual Basic, since screen capture in Visual Basic is much easier and code for this is available in the Knowledge Base section of Visual Basic.

Features

This article has the following features:

  • Capture the desktop
  • Capture a window
  • Capture a client area
  • Capture a control (e.g. Button)

In addition, it has the following, interesting but not so useful (in my view) features:

  • Track the X and Y coordinates of the captured image
  • Trace the color code of a specific point of the captured image

Option for color and position tracking are on the MainFrame window of the system and can only be used after capturing an image.

How to Use the Project

Download the project source, unzip the files to some folder, build the project, in case there are no errors at build-time, execute the project, an Icon of a Camera will appear in the System Tray (bar at the bottom of the screen). Right-Click on the Icon and a menu will pop-up, select the options from the menu.

Sample Image

Pop-up Menu

Option Task performed
Capture Desktop Captures a image of the System Desktop immediately
Capture Window Prompts to click on window to be captured
Capture Client Area Prompts to click on client area to capture
Capture Control Prompts to click on control to capture
Clear Image Clears captured image
Show Window Display the CapIT System Window
Close Closes the CapIT System

In addition to the pop-up menus, the CapIT System has it own main menu which cap be displayed when you select "Show Window" from the pop-up menu.

How It Works

When capturing window or client area or control, the system calls the function SetCapture() and waits for the user to click on some window on the Desktop which is to be captured. After clicking on the area to be captured, the system framework calls the member function void CCapITView::OnCaptureChanged(CWnd *pWnd) which calls WindowCapture(HWND hwnd) which in turn carries out the job of capturing the image (till the menu is disabled). After completion of capture, the system calls ReleaseCapture() to release SetCapture(). But in the case of capturing, the Desktop SetCapture() is not called, but directly calls WindowCapture(HWND hwnd) passing to it GetDesktopWindow()->m_hWnd and the system proceeds with capturing the Desktop image immediately, since there is only one Desktop area and its HWND is known to the System.

Note

The following member functions in the class CCapITView are borrowed from the MSDN sample WinCap. Could I have written them on my own, No Way.

  • HBITMAP CopyWindowToBitmap(CWnd* wnd , HWND hWnd, WORD fPrintArea)
  • HBITMAP CopyScreenToBitmap(LPRECT lpRect)
  • BOOL PaintBitmap(HDC hDC, LPRECT lpDCRect, HBITMAP hDDB, LPRECT lpDDBRect, HPALETTE hPal)
  • void DoSize(CWnd* wnd , HBITMAP ghBitmap)
  • void SetupScrollBars(CWnd* wnd , WORD cxBitmap, WORD cyBitmap)
  • void ReallyGetClientRect(CWnd* wnd , LPRECT lpRect)
  • WORD SaveDIB(HDIB hDib, LPSTR lpFileName)
  • WORD PaletteSize (VOID FAR * pv)
  • WORD DibNumColors (VOID FAR * pv)
  • HDIB ChangeBitmapFormat(HBITMAP hBitmap, WORD wBitCount, WORD dwCompression, HPALETTE hPal, HWND hwnd)
  • HANDLE AllocRoomForDIB(BITMAPINFOHEADER bi, HBITMAP hBitmap , HWND hwnd)
  • HPALETTE GetSystemPalette(HWND hwnd)
  • int PalEntriesOnDevice(HDC hDC)

Known Problems

Color of the saved image under Windows 98 is not the same as of the captured image, but I think it is nearly the same in Windows 2000.

Points of interest

The project uses a CScrollView instead of CView because if the image being captured is bigger in size (e.g., Desktop) then in the Frame Window you may not be able to capture the entire image since a CView will capture as per the CView Client Area size.

History

  • Version 1

License

This article has no explicit license attached to it, but may contain usage terms in the article text or the download files themselves. If in doubt, please contact the author via the discussion board below.

A list of licenses authors might use can be found here.


Written By
India India
Nothing to boast about

Comments and Discussions

 
GeneralScrolling dont work Pin
cppoju23-Nov-07 12:18
cppoju23-Nov-07 12:18 
GeneralAlt-Tab Pin
naykid319-Sep-06 7:41
naykid319-Sep-06 7:41 
GeneralRe: Alt-Tab Pin
Barretto VN19-Sep-06 21:38
Barretto VN19-Sep-06 21:38 
QuestionCan I get your email? Pin
Xueyan30-Jul-06 16:22
Xueyan30-Jul-06 16:22 
QuestionHow to capture a transparent window Pin
nowlex6-Jan-06 11:58
nowlex6-Jan-06 11:58 
AnswerRe: How to capture a transparent window [modified] Pin
Alexandru Matei28-May-06 20:08
Alexandru Matei28-May-06 20:08 
Generalcapture image without displaying application window Pin
Jagdish Vasani15-Feb-05 19:07
Jagdish Vasani15-Feb-05 19:07 
GeneralCapturing background Window Pin
tyounsi17-Jan-05 14:28
tyounsi17-Jan-05 14:28 
GeneralGood Work Dude. Pin
ThatsAlok20-Jul-04 23:20
ThatsAlok20-Jul-04 23:20 
GeneralI'm happy about this article Pin
Georgi Petrov26-May-04 1:42
Georgi Petrov26-May-04 1:42 
Generalcapturing desktop Pin
nandiniarun4-Apr-04 21:47
nandiniarun4-Apr-04 21:47 
GeneralRe: capturing desktop Pin
Barretto VN8-Apr-04 23:52
Barretto VN8-Apr-04 23:52 
GeneralRe: capturing desktop Pin
ThatsAlok20-Jul-04 23:17
ThatsAlok20-Jul-04 23:17 
Generalmore information Pin
Member 8587053-Feb-04 0:15
Member 8587053-Feb-04 0:15 
QuestionHow to capture a hidden window Pin
Sameers Javed3-Jan-04 6:13
Sameers Javed3-Jan-04 6:13 
AnswerRe: How to capture a hidden window Pin
Anonymous9-Mar-04 10:29
Anonymous9-Mar-04 10:29 
GeneralRe: How to capture a hidden window Pin
Bob McCown22-Jul-04 10:49
Bob McCown22-Jul-04 10:49 
GeneralRe: How to capture a hidden window Pin
GATJR10-Oct-06 6:40
GATJR10-Oct-06 6:40 
AnswerRe: How to capture a hidden window Pin
guangyen11-Mar-05 20:19
guangyen11-Mar-05 20:19 
GeneralRe: How to capture a hidden window Pin
Raj241131-Mar-05 19:58
Raj241131-Mar-05 19:58 
GeneralRe: How to capture a hidden window Pin
Faze793-Jun-05 1:00
Faze793-Jun-05 1:00 
GeneralRe: How to capture a hidden window Pin
kajok3-Oct-06 6:27
kajok3-Oct-06 6:27 
GeneralEverytime I pressed Capture desktop, it eats 4 MB of memory.. Pin
Mr. Jigar Mehta2-Jan-04 2:47
Mr. Jigar Mehta2-Jan-04 2:47 
QuestionHow to Capture Screen with DirectX ? Pin
hiver6-Dec-03 3:27
hiver6-Dec-03 3:27 
AnswerRe: How to Capture Screen with DirectX ? Pin
Member 84030715-Feb-04 21:42
Member 84030715-Feb-04 21:42 

General General    News News    Suggestion Suggestion    Question Question    Bug Bug    Answer Answer    Joke Joke    Praise Praise    Rant Rant    Admin Admin   

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.